Pivot retainer



Patented lune I9, i923.

NEFF@ FIFF;

HAL'V'OR O. HEM, OF TOLEDO, OHIO, ASSIGNOR TO TOLEDO SCALE COMPANY, OETOLEDO, OHIO, A CORPORATION OF NEW JERSEY.

PIVOT RETAINER.

Application filed April 12, 1920. Serial No. 373,433.

T 0 all whom t may concern Be it known that I, HALvoR O. HEM, a citizenof the United States, residing at Toledo, in the county of Lucas andState of Ohio, have 'invented certain new and useful Improvements inPivot Retainers, of which the following is a specification.

This invention relates to means for mounting knife-edge pivots such asare used in instruments and machines in which it is desirable to reducefriction to a minimum, and particularly to means for mounting suchpivots in scale levers. As such machines are now constructed theknife-edge pivots are usually placed in the mould in which the lever isto be cast and are thus fixed in place when the metal of the leversolidifies. In order that the scale may weigh properly, the pivots inscale leve-rs must be placed with great exactness and the practice ofcasting the levers with the pivots in place results in the loss of manycastings owing to the pivots having been improperly placed or havingshifted in the mould. Furthermore, the pivots lose their temper andoften warp during the casting process and must be re-shaped andre-hardened, which involves grinding and heattreating operations that,when the pivots are fixed in the lever, are difficult to carry out,especially if the lever be a heavy one. Where a pivot is thus fixed inplace it must be formed of a bar of sufhcient crosssection tc supportthe weight, and as these bars are of high-grade steel, their cost isconsiderable. The practice of inserting the pivots in holes drilled inthe lever is also followed to some extent, but such inserted pivots mustbe formed of even heavier bars than are used to form pivots which arefixed in place in casting and the cost of such inserted pivots istherefore also very great. The principal object of this invention is toprovide improved means whereby pivots containing a minimum amount ofexpensive metal may be securely and accurately fixed to a scale lever.

Another object is to provide means for securely fixing a pivot to alever so that the pivot may be readily detached and replaced.

Another object is to provide a thrust bearing member which also acts asa lock to hold the pivot in place.

Other objects 'and advantages will be apparent from the followingdescription, in

which reference is had to the accompanymgdrawings illustrating preferredembodiments of my invention and wherein similar reference numeralsdesignate similar parts throughout the several views.

In the drawings z- Figure 1 is a perspective view of the end of thelever equipped with my invention;

Figure 2 is a similar view of a fragment of a pivot retainer of myinvention, removed from the lever;

Figure 3r isa vertical section through the lever showing the retainer inelevation;

Figure 4 is a vertical cross-section through the retainer and pivottaken Substantially on the line 4 4 of Figure 3;

b Figure 5 is an elevation of the retaining Figure 6 is a verticalsection through a fragment of the lever showing another form of thedevice; y

Figure 7 is a side elevation of the parts shown in Figure 6;

Figures 8 and 9 are fragmentary vertical sections showing furthermodifications;

Figures 10 and 11 are respectively a side elevation and an edge view ofthe thrust bearing of the form shown in Figure 6;

'Figure 12 is an elevation of the thrust bearing shown in Figure 9; and

Figure 13 is a view at right angles to Figure 12.

Referring to the drawings in detail, and particularly to the form shownin Figures 1 to 5 inclusive, the lever 1 on which the pivots are to bemounted according to my invention is provided with tapered openings forreceiving pivot retainers 2, the central portions of whichv are tapered,as at 3, to fit snugly in the openings in the lever. Owing to thistapered formation the pivot retainers may be'driven into place so thatthey will be held with all necessary firmness, though they may, whennecessary, be driven out. Substantially cylindrical projections 4 areformed at the ends of the pivot retainer 2, and aligned,longitudinally-extending grooves 5 with their sides substantiallyparallel are milled in the sides of the project-ions 4 to receive thepivot bars 6. The pivot retainers may beof relatively inexpensivematerial, such as soft steel, while the pivot bars 6 may be formed ofpivot steel of the highest grade.

Extending obliquely through each yof the The ends 4 and cutting into thecorners of the grooves 5 are holes to receive retaining bolts 7, each ofwhich is provided with a rightangle notch 8 to receive the corner of thecorresponding pivot bar.- In order to provide thrust bearings for thebearing blocks (not shown) which are engaged by the knife-edge pivots 6when the scale is assembled, hardened steel pins 9 are driven intodepressions bored in the metal ofthe lever.y

In assembling the device the retainer 2 is driven into place in thelever and the bolts are placed in the bolt holes, with the notches 8substantially flush with thev corners of the grooves 5. The pivots arethen seated in the grooves andthe bolts 7 are tightened up, thussecurely clamping the pivots in place against the opposite walls of thegrooves 5.

The form shown in Figures 6, 7, 10 and l1 differs from the structurealready described in that the thrust rbearing 92L is in this formattached to the lever by means of screws and provided with a recessil()a intorwhich the inner corner of the pivot 6a fits when it is inplace. The pivot and retainer are thereby positively held againstturning movement.' pivot bars 6a in this form differ from those firstdescribed in that the sides opposite the knife edges are crowned, asshown at lla. If the bottom of the groove in the form shown in Figure lengages the bottom of the pivot at one side rather than uniformly, aheavy weight on the pivot edge will tend to tiltl it to one side andthereby affect the accuracy of the scale. The bottom of the groove will,however, engage the crowned surface substantially at its center, whetherthe parts are machined perfectly true or not, and a load on the pivotwill not' therefore tend to tilt it.

The form shown in Figure` 8 differs from that shown in Figures l to 5 inthat the thrust bearing 9b isk provided with a head and a shank so thatthe hole in the lever may be smaller than is the case with the formshown in'Figures l to 5.

In the form shown in Figures 9, l'and 14, the thrust bearing differsfrom the one shown in Figure 8 in that it is provided witha recess l0cto receive the corner of the pivot 6C and thereby hold it in place.

From the above description it is appar: ent that while the pivots 6sustains the wear, the shearing and bending strains are sustained by thepivot retainers. The pivots may therefore be made of ample strength withthe use of very little expensive inetal. It is also apparent that thepivots may be removed for re-sharpening or `replacement without removingthe scale levers, and that when the parts are assembled they are firmlyheld against relative rfliovement'. v

be understood that the invention is susceptibleto variation,modification and change n within the spirit and scope of the subjoinedclaims.

l-Iavingv described my invention, I claim:

1. In a device of the class described, in i combination, a lever havinga round bore therethrough, a round pivot retainer snugly fitting in saidbore, said pivot retainer having a groove therein, a pivot bar seatedVin said groove, and wedging means for securing said pivot bar in saidgroove.

2. In a `device of the class described, in combination, a member havinga groove therein, a pivot barseated in said groove, and a notched bolt;passing through. said member and wedgingly engaging said p'ivot bar. f

3. In a deviceV of the class described, combination, a member having agroove therein, a bolt passing through said mem# ber and having a notchsubstantially registering with one corner of said groove, a pivot barseated in said groove and notch, and means for forcing said boltlongitudinally and thereby clamping said pivot bar in said groove.

4. In a device of the class described, in combination, a member having asubstantially rectangular groove therein and a bore cutting one cornerof said groove, a bolt in said bore having a notch substantiallyregistering with theicornerv of said groovea pivot bar seated in saidgroove, and means for moving said bolt longitudinally.

5. In a device of the classy described, combination, a member having asubstantially fiat-bottomed groove therein, and a pivot bar immovablyseated in said groove and having a crowned surface engaging the bottomof said groove.

6. In a device of the class described, in combination, a member having asubstantially rectangular groove therein and a ybore cutting one cornerof said groove, a bolt in said bore having a notch substantiallyregistering with the corner of said groove, a pivot barseated in saidgroove and having a crowned surface engaging the bottom of said groove,and means for moving said bolt longitudinally. 4

7. In a device of the class described, in combination, a. lever member,a knife edge pivot secured thereto, and a pivot at one end of saidthrust bearing'having a notch receiving a portion of said pivot. l

8. In a device of the class described, in combination, a member having asubstantially rectangular groovel therein and a bore cutting one cornerof said groove, a bolt in said bore having a notch substantially. regiio seated in said groove, and a thrust bearing 10 secured to said lever,sald thrust bearlng having a notch receiving a portion of said pivot.

HALVOR O. HEM.

Witnesses:

C. E. WILooX, C. O, MARSHALL.

